Dead-line phase identification system and method thereof

ABSTRACT

A system and method for dead-line conductor phase identification is provided. The system includes a receiver unit having a set of current sensors, such as current transformers. The receiver unit current sensors are coupled to conductors having a known phase in a multiphase power line. The current sensors are positioned adjacent a transformer connected to a section of the power line having an open circuit condition. A transmitter unit transmits a current signal on to a conductor at the open circuit section of the power line. The current sensors detect the current signal and the receiver unit transmits a signal to the transmitter unit identifying the phase on which the current signal was transmitted.

BACKGROUND OF THE INVENTION

This application is a divisional application of U.S. patent applicationSer. No. 12/126,447, filed on May 23, 2008 entitled “DEAD-LINE PHASEIDENTIFICATION SYSTEM AND METHOD THEREOF”.

The present invention relates generally to a system for determining theelectrical phase of a conductor and more particularly to a system thatdetermines the electrical phase of a conductor with an open circuitcondition in a multiphase electrical power line.

The generation of electrical power is generally performed in largecentrally located plants. These power plants use a fuel, such as coal ornatural gas, to generate heat to create steam. The steam then expandsthrough a turbine causing the turbine to rotate. This rotation istransferred to an electrical generator that creates rotating magneticfields that produce electricity through induction. This type ofelectrical power is known as alternating current. Electrical generatorsof this type are typically arranged to generate three electricalcurrents or “phases” that are arranged 120 degrees apart. These phasesare typically designated as the “A”, “B”, and “C” phases.

Each of the electrical phases is transmitted on a separate conductorwith a layer of insulation surrounding each of the conductors. Theinsulation allows the routing of the conductors together from thegeneration plant to the end users while keeping the conductorselectrically isolated from each other. Unfortunately, due to a varietyof factors, including new construction, network expansion, environmentaleffects, or abrasions and mechanical wear for example, an open circuitcondition may occur. In some cases the insulation between the electricalphases may deteriorate causing an electrical fault. These type of faultsmay also be the result of other causes, such as lightening strikes, ortrees falling across the power lines for example. When a gap is createdin the insulation a dielectric breakdown may occur causing aphase-to-phase short. This type of failure releases of a large amount ofenergy damaging the conductors and may result in the conductorphysically breaking causing an open circuit condition.

When an open circuit condition such as that described above occurs,personnel are dispatched by the utilities to repair or reconnect theconductors. In the case of a failure caused by a phase-to-phase short,the conductors may be split and it is difficult for the lineman toidentify which conductor is associated with which electrical phase.Identification of the correct phase is important for the properoperation of the power system. The crossing of phases during repairswill result in having to re-work the splice and risk potential failuresthat could damage the conductors and other equipment in the electricalnetwork.

Before any work can be performed on the conductors, the feeder circuitin the distribution network needs to be identified and protected(grounded) for work. The method of identifying the feeder circuit willdepend on how the conductors were damaged. If only one of the conductorsis broken, applying a tracing current to the two remaining conductorscan identify the feeder circuit. This technique is effective because theremaining conductors provide a return path for the tracer current.

When the fault causes a break in all three conductors, the tracingcurrent method will not be effective since there is no return path. Inthis case, a spear is applied to the cable shorting all threeconductors. This creates a path for the tracing current so that thefeeder can be identified. However, the phase of each cable cannot beidentified with the spear in place.

Commonly, the identification of the phases and the repairs of the cablesare performed by separate personnel: a Splicer who repairs and splicesthe conductors back together, and a phase identification crew. Separatepersonnel are used because the tracing method used for identifying thephase requires additional special training. Further, the phaseidentification crew needs to locate and travel to the transformerslocated on either side of the section having an open circuit condition.The transformers are grounded, isolating the section having an opencircuit condition. The Splicer then prepares the conductors forsplicing. The identification crew applies an audio frequency tracingtone to the conductors on the transformer side of the conductor and thentravels back to the section having the open circuit condition. The phaseidentification crew uses the trace tone to identify and label the phaseon each of the conductors. This is repeated for each set (3 conductors)of cable ends that need to be spliced. In the case of medium voltagetransmission cables, the transformers are located a distance from thelocation of the failure. It is time consuming for the phaseidentification crew to travel, set up to enter an underground structureto perform the splice, and then perform the testing required toestablish the phases. In addition, multiple trips may be required. Thisis performed for each set of cable ends (a minimum of two).

Once the conductors are labeled, the Splicer may complete the repair andsplice the conductors on either side of the open circuit section backtogether. The power lines may then be re-energized and electricalservice restored.

The process of identifying and repairing conductors in a three phasesystem is time consuming and expensive. Further, the above process ofapplying a tracing current is not feasible when an open circuit isencountered. While the existing processes and systems for identifyingand repairing three phase conductors are suitable for their intendedpurposes, there still remains a need for improvements particularlyregarding the reduction of the amount of time required to make repairs.Further improvements are also needed to increase the reliability of thesplicing repairs to avoid the need to re-work the repair.

SUMMARY OF THE INVENTION

A system for identifying an electrical phase of a conductor is provided.The system includes a first current sensor electrically coupled to afirst controller. A first communications device is electrically coupledto the first controller. A second communications device is operablycoupled to receive a signal from the first communications device. Asecond controller is electrically coupled to the second communicationsdevice and a power supply. A switching circuit is electrically coupledto the power supply and the second controller. A test conductor iscoupled to the switching circuit.

A method of determining an electrical phase of a conductor in athree-phase cable having a first end and a second end is also provided.The method includes the step of coupling a first current sensor to afirst conductor on the first end. A second current sensor is coupled toa second conductor on the first end. A third current sensor is coupledto a third conductor on the first end. An electrical current is appliedto a conductor on the second end. A signal is transmitted in response todetecting a current on the first conductor, the second conductor, or thethird conductor on the first end. Finally, a visual indication isprovided if the current was detected on the first conductor.

A method of joining conductors in a multiphase electrical power linehaving a section with an open circuit condition is also provided. Themethod includes the steps of grounding a first transformer. A first setof current sensors is coupled to the conductors of the multiphaseelectrical power line adjacent to the first transformer, wherein each ofthe current sensors in the first set of current sensors is associatedwith one of the conductors. A first current is transmitted to one of theconductors adjacent the multiphase electrical power line failed section.The first current is detected with one of the first set of currentsensors. Finally, a first signal is transmitted indicating whichconductor the first current was detected, wherein the first signal alsoincludes a signal indicating that the first current was detectedadjacent to the first transformer.

A system for identifying an electrical phase of a conductor is alsoprovided. The system includes a receiver unit having at least onecurrent sensor. A controller is operably coupled to current sensor and acommunications transmitter. A transmitter unit is provided having atleast one test lead and a neutral lead. The transmitter unit has acontroller operably coupled to the test lead and the neutral lead. Acommunications receiver is operably coupled to the controller and thecommunications transmitter. The transmitter controller is arranged toreceive data and instructions as inputs and provide data andinstructions as outputs. The transmitter controller data inputsdescribe: a phase identification that a current signal was detected; anidentification of a transformer where the current signal was detected; alocation of a failure; a number of conductors involved with the failure;a type of repair; a repair start time; a repair end time; and anidentity of a repair personnel. The transmitter controller instructioninputs enable the transmitter controller to determine when to transmitdata. The transmitter controller output data describes: the location ofa failure; the number of conductors involved with the failure; the typeof repair; the repair start time; the repair end time; and the identityof a repair personnel. The transmitter controller instruction outputsenable the activation of an indicator associated with the identifiedphase conductor.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, which are meant to be exemplary and notlimiting, and wherein like elements are numbered alike:

FIG. 1 is a schematic illustration of a utility electrical distributionsystem;

FIG. 2 is a perspective view illustration of a three phase conductor atthe location of a fault;

FIG. 3 is a schematic illustration of an exemplary embodiment dead-linephase identification system;

FIG. 4 is a schematic illustration of an exemplary embodiment receiverunit for the phase identification system of FIG. 3;

FIG. 5 is a schematic illustration of an exemplary embodimenttransmitter unit for the phase identification system of FIG. 3;

FIG. 6 is a schematic illustration of an alternate embodiment dead-linephase identification system;

FIG. 7 is a schematic illustration of the phase identification system ofFIG. 6 arranged to validate the splice repair;

FIG. 8 is a schematic illustration of an alternate embodiment dead-linephase identification system; and

FIG. 9 is a schematic illustration of another alternate embodiment phaseidentification system.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary embodiment of a utility electricaldistribution network 20. The utility network 20 includes one or morepower plants 22 connected in parallel to a main distribution network 24.The main distribution network 24 includes aboveground portions 26 thatutilize towers to carry three phase conductors. It should be appreciatedthat as used herein, the term “conductor” means a medium capable oftransferring electrical power, including but not limited conductors andcables for example. The main distribution network 24 may further includeunder-ground portions 28. The under-ground portions 28 are typicallyaccessed through manholes 30. The power plants 22 may include, but arenot limited to: coal, nuclear, natural gas, or incineration powerplants. Additionally, the power plants 22 may include one or morehydroelectric, solar, or wind turbine power plants. It should beappreciated that additional components such as transformers, switchgear,fuses and the like (not shown) may be incorporated into the utilitynetwork 20 as needed to ensure the safe and efficient operation of thesystem. The utility network 20 may be also be interconnected with one ormore other utility networks to allow the transfer of electrical powerinto or out of the utility network 20.

The main distribution network 24 typically consists of medium voltagepower lines, less than 50 kV for example, and associated distributionequipment which carry the electrical power from the point of productionat the power plants 22 to the end users located on local electricaldistribution networks 34, 36. In the exemplary embodiment, the maindistribution network 24 is a three-phase electrical network having “A”phase, a “B” phase, a “C” phase and a neutral for example. The localdistribution networks 34, 36 are connected to the main distributionnetwork 24 by substations 32 which adapt the electrical characteristicsof the electrical power to those needed by the end users. Substations 32typically contain one or more transformers, switching, protection andcontrol equipment. The main distribution network 24 may includetransformers 40, 42, 44 that modify the characteristics of theelectrical power during transmission. Larger substations may alsoinclude circuit breakers to interrupt faults such as short circuits orover-load currents that may occur. Substations 32 may also includeequipment such as fuses, surge protection, controls, meters, capacitorsand voltage regulators.

The substations 32 connect to one or more local electrical distributionnetworks, such as local distribution network 34, for example, thatprovides electrical power to a commercial area having end users such asan office building or a manufacturing facility. Local distributionnetwork 34 may also include one or more transformers that further adaptthe electrical characteristics of the delivered electricity to the needsof the end users. Substation 32 may also connect with other types oflocal distribution networks such as residential distribution network 36.The residential distribution network 36 may include one or moreresidential buildings and also light industrial or commercialoperations.

Due to a variety of factors, including environmental effects such aslightening strikes for example, new construction, or network expansionactivities the conductors in the utility network 20 may experience anopen circuit condition, such as a failure caused by a phase-to-phaseshort for example. These open circuit conditions may occur anywhere inthe network 20 including in the aboveground section 26, at locationdesignated as 46 for example. The open circuit condition may also occurin the belowground section 28, at the location designated as 48 forexample. The failure of the conductor in the main distribution network24 typically results in the loss of electrical power service to thelocal distribution networks 34, 36 and the end user customers. Theutility provider that operates the distribution network 24 will promptlydispatch repair crews to make the appropriate repairs so service may berestored.

The open circuit condition, such as a failure for example, causes abreak in the cable 50 into a first section 51 and a second section 52,as shown in FIG. 2. Additional issues are created when the open circuitcondition occurs in a three-phase transmission section of the utilitynetwork 20 such as at location 46 or location 48 for example. When anopen circuit occurs in these areas, each section of the cable 50 hasthree individual phase conductors 54, 56, 58 and phased conductors 60,62, 64 as illustrated in FIG. 2. Before the connections may be made, theindividual phase conductors need to be correctly identified. If thephase conductors from section 51 are incorrectly spliced with thecorresponding phase conductors in section 52, damage may result to theequipment on distribution network 24. It should be appreciated that thisfailure may occur at any location along the distribution network 24. Itshould be further appreciated that these types of conditions may alsooccur in any type of electrical distribution, electrical transmission orpower delivery system. As used herein, an electrical distribution,electrical transmission or power delivery system means any powergeneration system, power transmission system, power distribution systemand may also include commercial, industrial, residential or nauticalpower delivery systems. The electrical transmission system may also havemore than three phases, such as a six-phase or ten-phase transmissionsystem. Further, while for exemplary purposes, the open circuitcondition will be discussed herein as being located at position 48, theclaimed subject matter is not so limited.

Referring now to FIG. 3, an exemplary embodiment dead-line phaseconductor identification system 100 and method will be discussed. Theopen circuit condition at location 48 results in a break in theconductor 50 into two sections 51, 52 as discussed above. The utilitydispatches a repair crew that first connects a ground 102 to thetransformer 40, 42 grounding the transformers that are located on eitherside of location 48. By grounding the transformers 40, 42, the cablesections 51, 52 are electrically isolated from the distribution network24, allowing the repairs and connections to be made. After grounding thetransformers 40,42, the repair crew couples a phase identifier receiverunit 104, 106 to the cable 51, 52 respectively. Each receiver unit 104,106 includes three current sensors 108, 110, 112 that are coupled to the“A” phase conductor 54, 60, the “B” phase conductor 56, 62, and the “C”phase conductors 58, 64 respectively. In one alternate embodiment, thereceiver unit 104, 106 has only two current sensors, however, the use ofthree current sensors provides additional advantages in reliablyidentifying the phase of the conductors. It should be appreciated thatsince these connections are made at the transformer, the labels andmarkings on the transformer allow the repair personnel to know whichconductor is associated with which phase.

The current sensors 108, 110, 112 may be any type of sensor that iscapable of detecting the presence of electrical current on a conductor.In the exemplary embodiment, the current sensors 108, 110, 112 arecurrent transformers. In general, a current transformer is a device thathas a primary winding and a secondary winding. Current is induced in thesecondary winding due to magnetic fields generated by alternatingcurrent in primary winding. The current in the secondary winding isproportional to the current flowing in the primary. Current transformersprovide a convenient means for measuring large currents by isolating themeasuring equipment from the high current conductor. The currenttransformer also provides advantages in that it allows measurement ofthe current without disrupting or directly coupling to the targetcircuit. In the exemplary embodiment, the current transformers 108, 110,112 are coupled to the individual phase conductors to generate a currentthat is proportional the current flowing through the individual phaseconductors.

The receiver unit 104, 106 includes a detection circuit 114 as shown inFIG. 4. The detection circuit 114 is coupled to the current sensors 108,110, 112 by leads 116, 118, 120 respectively. Detection circuit 114 iscapable of converting the analog voltage or current level provided bysensors 108, 110, 112 into a digital signal indicative of the currentsignal on conductors 54, 56, 58, 60, 62 64. Alternatively, sensors 108,110, 112 may be configured to provide a digital signal to detectioncircuit 114 or a controller 122, or an analog-to-digital (A/D) convertermaybe coupled between sensors 108, 110, 112 and detection circuit 114 toconvert the analog signal provided by sensors 108, 110, 112 into adigital signal for processing by controller 122.

The detection circuit 114 transmits a signal to a controller 122. Thecontroller may be any suitable control device capable of receivingmultiple inputs and providing control functionality to multiple devicesbased on the inputs. The controller 122 is capable of accepting data andinstructions, executing the instructions to process the data, andpresenting the results. Controller 122 may accept instructions throughuser interface 124, or through other means such as but not limited toelectronic data card, voice activation means, manually operableselection and control means, radiated wavelength and electronic orelectrical transfer. Therefore, controller 122 can be a microprocessor,microcomputer, a minicomputer, an optical computer, a board computer, acomplex instruction set computer, an ASIC (application specificintegrated circuit), a reduced instruction set computer, an analogcomputer, a digital computer, a molecular computer, a quantum computer,a cellular computer, a superconducting computer, a supercomputer, asolid-state computer, a single-board computer, a buffered computer, acomputer network, a desktop computer, a laptop computer, or a hybrid ofany of the foregoing.

Controller 122 uses the digital signals to act as input to variousprocesses, including but not limited to a Fast Fourier Transform (FFT)signal analysis for determining if a current signal is being transmittedover the conductors. As will be discussed in more detail below, the FFTsignal analysis allows the controller 122 to determine the level andfrequency of the current signal. Thus, the controller 122 candistinguish the desired current signals from erroneous currents inducedby surrounding power lines.

Data received from sensors 108, 110, 112 may be displayed on userinterface 124, which is coupled to controller 122. User interface 124may be an LED (light-emitting diode) display, an LCD (liquid-crystaldiode) display, a CRT (cathode ray tube) display, or the like. A keypadmay be coupled to user interface 124 for providing data input tocontroller 122.

A data communications transceiver 126 is coupled to receive signals fromthe controller 122. As will be discussed below, when the controller 122detects a current on the conductors, a signal is transmitted via thedata communications transceiver 126 indicating which conductor phase thecurrent signal was detected. The signal may also incorporate anidentification data indicating either the receiver unit ID or thetransformer ID. The data communications transceiver 126 may be a wiredor wireless communications device, such as but not limited to a cellularmodem, a code division multiple access (CDMA) modem, a global system formobile (GSM) communications modem, a universal mobile telecommunicationssystem (UMTS) modem. The communications transceiver 126 may also bebased on other protocols or communications technologies including butnot limited to: TCP/IP, IEEE 802.11, RS-232, RS-485, Modbus, IrDA,infrared, radio frequency, electromagnetic radiation, microwave,power-line, telephone, fiber-optics, barcode, and laser.

Alternatively, the communications transceiver 126 may couple theController 122 to external computer networks such as a local areanetwork (LAN) and the Internet. The LAN interconnects one or more remotecomputers, which are configured to communicate with controller 122 usinga well-known computer communications protocol such as TCP/IP(Transmission Control Protocol/Internet Protocol), RS-232, ModBus, andthe like. Additional receiver units 104, 106 may also be connected toLAN with the controllers 122 in each of these receiver units beingconfigured to send and receive data to and from remote computers. LANmay be connected to the Internet. This connection allows controller 122to communicate with one or more remote computers connected to theInternet.

Controller 122 includes operation control methods embodied inapplication code. These methods are embodied in executable computerinstructions written to be executed by a processor, typically in theform of software. The software can be encoded in any language,including, but not limited to, assembly language, VHDL (Verilog HardwareDescription Language), VHSIC HDL (Very High Speed IC HardwareDescription Language), Fortran (formula translation), C, C++, VisualC++, Java, ALGOL (algorithmic language), BASIC (beginners all-purposesymbolic instruction code), visual BASIC, ActiveX, HTML (HyperTextMarkup Language), and any combination or derivative of at least one ofthe foregoing. Additionally, an operator can use an existing softwareapplication such as a spreadsheet or database and correlate variouscells with the variables enumerated in the algorithms. Furthermore, thesoftware can be independent of other software or dependent upon othersoftware, such as in the form of integrated software.

The controller 122 may include further components as necessary toperform the execution of the computer instructions. These componentsinclude processors, random access memory (RAM), read only memory (ROM),nonvolatile memory (NVM) and I/O controllers. The ROM device stores anapplication code, e.g., main functionality firmware, includinginitializing parameters, and boot code, for a processor. Applicationcode also includes program instructions for causing a processor toexecute any dead-line phase identification operation control methods. ANVM device is any form of non-volatile memory such as an EPROM (ErasableProgrammable Read Only Memory) chip, a disk drive, or the like. Storedin NVM device are various operational parameters for the applicationcode. The various operational parameters can be input to NVM deviceeither locally, using user interface 124 or a remote computer, orremotely via the Internet using remote computer. It will be recognizedthat application code can be stored in NVM device rather than a ROMdevice.

A power supply 128 is coupled to the controller 122, the detectioncircuit 114 and the transceiver 126 to provide the electrical power needby the components and circuits discussed above. The power supply 128 maybe self-contained, such as a battery for example, that transmits adirect current (DC) electrical power to the receiver unit 104, 106.Alternatively, the power supply 128 may connect to an external powersource, such as a 120V, 60 Hz outlet for example, and convert theelectrical power to have the characteristics needed by the receiver unit104, 106.

Referring back to FIG. 3, once the transformers 40, 42 have beengrounded, utility personnel may proceed to prepare the section having anopen circuit condition. The utility personnel first prepare theconductors by removing a sufficient amount of insulation from each cableto expose enough of the conductor portion to allow it to be spliced withthe corresponding conductor on the opposite side of the open circuitpoint. The service personnel then couple a test lead 132 fromtransmitter unit 130 to one of the conductors that has been prepared forsplicing. A second lead 134 from transmitter unit 130 is coupled to theneutral to complete the circuit.

The transmitter unit 130 is described in reference to FIG. 5. The leads132, 134 are coupled to a switching circuit 136. As will be discussedbelow, the switching circuit applies a current signal from power supply138 to the test lead 132 and the conductor to which it is connected. Acontroller 140 is coupled to the switching circuit 140 and power supply138. The controller 140 is substantially similar in construction tocontroller 122 above. The controller 140 is capable of accepting dataand instructions, executing the instructions to process the data, andpresenting the results. Controller 140 may accept instructions throughuser interface 142, or through other means such as but not limited toelectronic data card, voice activation means, manually operableselection and control means, radiated wavelength and electronic orelectrical transfer.

As was discussed above with reference to controller 122, controller 140is includes operation control methods embodied in application code.These methods are embodied in executable computer instructions writtento be executed by a processor, typically in the form of software. Thesoftware can be encoded in any language, including but not limited tothose discussed above with respect to controller 122. The controller 122further has additional components, such as processors, ROM, RAM, NVM andI/O controllers to perform the executable computer instructions,transmit and receive signals.

The controller 140 is coupled to receive signals from receiver units104, 106 via communications receiver device 144. The communicationstransceiver 144 is arranged to communicate with the communicationstransceiver 126 and therefore will include communications protocols thatare compatible with the communications transceiver 126. As such, thecommunications transceiver 144 may be a cellular modem, a code divisionmultiple access (CDMA) modem, a global system for mobile (GSM)communications modem, a universal mobile telecommunications system(UMTS) modem. The communications transceiver 126 may also be may also bebased on other protocols or communications technologies including butnot limited to: TCP/IP, IEEE 802.11, RS-232, RS-485, Modbus, IrDA,infrared, radio frequency, electromagnetic radiation, microwave,power-line, telephone, fiber-optics, barcode, and laser. Thecommunications transceiver 126 may further be connected and communicatevia a LAN or the Internet.

The data received from communications transceiver 144 may be displayedon user interface 142, which is coupled to controller 140. Userinterface 142 may be an LED (light-emitting diode) display, an LCD(liquid-crystal diode) display, a CRT (cathode ray tube) display, or thelike. A keypad may be coupled to user interface 142 for providing datainput to controller 140. In the exemplary embodiment, the user interface142 includes three LED indicators, one for the “A” phase 146, one forthe “B” phase 148, and one for the “C” phase 150. During operation, whenthe receiver unit detects a current signal on one of the conductors, asignal is transmitted to the transmitter unit 130 and the controller 140activates the LED 146, 148, 150 that corresponds to the phase thecurrent signal was detected. In one embodiment, the user interface 142also includes a display 152 that indicates which receiver unit 104, 106received the current signal.

In operation, the utility personnel couple the test lead 132 to one ofthe conductors at the location of the open circuit. The neutral lead 134is coupled to the neutral. A removable device, such as an alligatorclamp for example, may accomplish the coupling of the leads 132, 134.Once the connections have been made, the utility personnel activate thetransmitter 130 using user interface 142. The controller 140 transmits acurrent signal from power supply 138 via switching circuit 136. Thesignal is transmitted into the conductor, conductor 54 for example. Inthe exemplary embodiment, the current signal generated by thetransmitter unit 130 is between a first and second current threshold andat a predefined voltage, such as 12 volts and between 1.5 amps-12 amps,and preferably between 6 amps-10 amps for example. In some embodiments,the frequency of the current signal is below a first threshold, such asbetween 30 Hz-45 Hz for example. In other embodiments, the frequency ofthe current sign above a second threshold, such as 80 Hz-100 Hz forexample. During testing of the exemplary embodiment, an injectioncurrent signal of approximately 12 volts, 9.2 Amps at frequency of 30-45Hz was transmitted and detected by a receiver unit 13 miles away. Itshould be appreciated that it is advantageous to utilize frequenciesthat are not close to 60 Hz which allows the receiver unit 104, 106 tofilter out any 60 Hz signals it may detect. It is desired to filter outthe 60 Hz signals since these may be induced in the cable 50 bysurrounding electrical transmission cables.

Once the current signal is generated by the transmitter unit 130, thesignal should be received by one of the sensors 108, 110, 112. If thecurrent signal was transmitted on conduit 54 as used in the exampleabove, then the current sensor 112 will receive and detection circuit114 will detect the current signal. The controller 122 performs a FFTsignal analysis and filters out any signals in the 60 Hz region. If asignal meeting the predetermined characteristics or thresholds isdetected (e.g. having a frequency between 30 Hz-45 Hz or 80 Hz-100 Hz),the controller 122 transmits a signal via communications transceiver 126to the transmitter unit 130.

Upon receiving a signal from receiver unit 104, the controller 140activates the appropriate LED on user interface 142. In the exampleabove, where the current signal was transmitted on conductor 54, thecontroller would activate LED 146, which would indicate to the utilitypersonnel that the test lead 132 is coupled to the “A” phase. Theutility personnel then label the conductor with the appropriate phaseand move the test lead to the next conductor. This process is repeateduntil all of the conductors have been identified and properly labeled.The conductors and neutral may then be spliced together and electricalservice restored.

The dead-line phase identification system 100 provides a number ofadvantages in reducing costs and reducing the amount of time to completerepairs and restore electrical service. Since the identification signalis sent wirelessly, the process may be conducted with one utilitypersonnel located at the site of the open circuit. The detecting deviceis placed at the transformer location when the ground is placed andremoved, hence no additional trip is required to the transformer. Thisavoids the need for additional personnel to travel from the transformerto the open circuit site and back again. In addition, the Splicer is nonproductive during the time the phases are established when using thepresent method. This is especially advantageous when multiple opencircuits are occurring during high load periods and crewing is scarce.Further, the embodiments described herein may be utilized when opencircuit failures occur.

An alternate embodiment dead-line phase identification system 100 isillustrated in FIG. 6. This arrangement allows the utility personnel totest the conductors on both cable sections 51, 52 simultaneously. Thisfurther saves time during the identification of the phases. Thetransmitter unit includes a user interface 142 indicators correspondingto the test leads 132, 134 and 154, 156. This arrangement allows for thetesting of both sides of the open circuit simultaneously.

Another embodiment provides further advantages in validating the splicedconductors simultaneously in both directions before energizing the cable50 as illustrated in FIG. 7. Once the splices have been completed, theutility personnel may validate the splice by placing the test leads 132,154 on each of the conductors in turn. The current signal is transmittedas before except that the signals are transmitted in both directions,meaning towards transformer 40 and transformer 42 simultaneously. If thesplice has been performed correctly, then the LED's that correspond tothe same phase for each transformer 40, 42 should activate on the userinterface 124. In this way, the utility personnel may validate thesplice before applying the insulator devices around the conductor.

Another alternate embodiment is illustrated in FIG. 8. In thisembodiment, the open circuit in the distribution network 24 occurs in alocation having multiple electrical transmission conductors in closeproximity. A failure or open circuit of one of the electricaltransmission conductors may result in damage to the surroundingtransmission conductors as well. In this embodiment, the utilitypersonnel must enter the area 158 where the failure occurred, sometimesreferred to as a splicing pit, and not only identify the conductorsphase, but also which transformer the conductor is associated with.

As before, one or more utility crews ground each of the affectedtransformers 40, 42, 160, 162, 164, 166. Once the transformers aregrounded, receiver units 104, 106, 168, 170, 172, 174 are coupled totheir respective transformers. In the exemplary embodiment, the utilitycrew inputs a transformer identification, such as a location or serialnumber for example, into each of the receiver units via their respectiveuser interfaces. Alternatively, each transformer may have an identifier,such as a serial number or a location designation for example, and theutility crew contacts the personnel located at the splicing pit 158 andnotifies them of which receiver unit is located at a particulartransformer. In one embodiment, the receiver units are permanentlymaintained at the respective transformers and activated for operationonce the transformer has been grounded.

With the transformers grounded, the utility personnel may enter thesplicing pit 158 and prepare the conductors for splicing. Theidentification of the phases proceeds as before with the utilitypersonnel attaching the test lead 132 to a conductor and thetransmission of the current signal. In this embodiment, the receiverunits, in addition to transmitting a signal of which phase the currentsignal was detected, also transmit data on the identity of the receiverunit, or the location of the transformer entered by the utility crew.

In another alternate embodiment illustrated in FIG. 9, the controller140 includes methods and instructions for communicating with a centrallocation. In this embodiment, there is shown the transmitter unit 130including controller 140. The controller 140 receives input and outputdata 176, and instructions 178, 180. The data 176 may come from avariety of sources, such as transmitted data, database data, transformerdata, operator input data, and other data. The data 176 may also bedescribed in terms of the type of information represented by the data,such as the location of the open circuit 184, the number of conductorsinvolved 186, the type of repair made 188, the repair start time 190,the repair end time 192; the identification of the repair personnel 194;the identification of the conductor on which the current signal wasdetected 198, and the identification of the transformer where thecurrent signal was detected 200. The controller 140 may further receiveinstruction inputs 180 that include the activating 202 of an LED on userinterface 142.

The data and instruction outputs from transmitter unit 130 may betransmitted to a central control 182, a shift supervisor 185, thetransformers 40, 42, or another controller associated with the maindistribution network 24. This data may be used advantageously to help inthe cost effective and efficient scheduling of the repair personnel forexample. The controller may also receive instruction inputs 196 that thedata may require transmitting the data using several differentcommunication protocols, such as an email to a shift supervisor forexample. The data could indicate that the repair has been or is nearingcompletion. This data can then be used advantageously by the shiftsupervisor to reallocate resources in a more efficient manner, such asby sending crews to retrieve the receiver units from the transformer forexample. This data may further be used as a historical record of therepair and allow the utility to track performance and reliability of thedistribution network 24 over time.

It should be appreciated that while the embodiments described hereinrefer to the device 130 and the devices 104, 106 as being the“transmitter” and “receiver” respectively, the functionality of thesedevices many be reversed without deviating from the scope of the claimedinvention. For example, the device 104 may transmit a signal that isreceived by the device 130. Alternatively, the device 130 may bepositioned adjacent the transformer 40 while the device 104 ispositioned at the location of the break in cable 50.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

1. A method of determining an electrical phase of a conductor in a three phase cable having a first end and a second end, said method comprising: coupling a first current sensor to a first conductor on said first end; coupling a second current sensor to a second conductor on said first end; coupling a third current sensor to a third conductor on said first end; applying an electrical current to a conductor on said second end; transmitting a signal in response to detecting said electrical current on said first conductor, said second conductor, or said third conductor on said first end; and, providing a visual indication if said electrical current was detected on said first conductor.
 2. The method of claim 1 further comprising the step of providing a visual indication if said electrical current was detected on said second conductor.
 3. The method of claim 2 further comprising the step of providing a visual indication if said current was detected on said third conductor.
 4. The method of claim 1 wherein said electrical current is between a first and second current threshold.
 5. The method of claim 4 wherein said electrical current is at a predefined voltage.
 6. The method of claim 4 wherein said electrical current has a frequency in a predefined frequency range below a predefined threshold.
 7. The method of claim 4 wherein said electric current has a frequency in a predefined frequency range above a predefined threshold.
 8. A method of joining conductors in a multiphase electrical power line having a section with an open circuit condition, said method comprising: grounding a first transformer; coupling a first set of current sensors to said conductors of said multiphase electrical power line adjacent to said first transformer, wherein each of said current sensors in said first set of current sensors is associated with one of said conductors; transmitting a first current to one of said conductors adjacent said multiphase electrical power line section; detecting said first current with one of said current sensors in said first set of current sensors; and, transmitting a first signal indicating which of said conductors detected said first current, wherein said first signal also includes a signal indicating that said first current was detected adjacent to said first transformer.
 9. The method of claim 8, further comprising: grounding a second transformer; coupling a second set of current sensors to said conductors of said multiphase electrical power line adjacent to said second transformer, wherein each of said current sensors in said second set of current sensors is associated with one of said conductors; transmitting a second current to one of said conductors adjacent said multiphase electrical power line section; detecting said second current with one of said current sensors in said second set of current sensors; and, transmitting a second signal indicating which of said conductors detected said second current, wherein said second signal also includes a signal indicating that said current was detected adjacent to said first transformer.
 10. The method of claim 9, further comprising: identifying a phase for each of said conductors in said multiphase electrical power line section as indicated by said first signal and said second signal; splicing together said conductors having an identical phase; transmitting a third current to said spliced together conductors; detecting said third current with said first set of current sensors; detecting said third current with said second set of current sensors; transmitting a third signal indicating which phase conductor said third current was detected by said first set of current sensors; and, transmitting a fourth signal indicating which phase conductors said third current was detected by said second set of current sensors.
 11. A system for identifying an electrical phase of a conductor, said system comprising: a receiver unit having at least one current sensor, a controller operably coupled to said current sensor and a communications transmitter operably coupled to said controller; a transmitter unit having at least one test lead and a neutral lead, said transmitter unit having a controller operably coupled to said test lead and said neutral lead, and a communications receiver operably coupled to said controller and said communications transmitter, wherein: said transmitter controller receives data and instructions as inputs and provides data and instructions as outputs; said transmitter controller data inputs describing, a phase identification that a current signal was detected, an identification of a transformer where said current signal was detected, a location of a failure, a number of conductors involved with the failure, a type of repair, a repair start time, a repair end time, and an identity of a repair personnel; said transmitter controller instruction inputs enabling said transmitter controller to determine when to transmit data; said transmitter controller output data describing said location of a failure, said number of conductors involved with the failure, said type of repair, said repair start time, said repair end time, and said identity of a repair personnel; and, said transmitter controller instruction outputs enabling the activation of an indicator associated with said identified phase conductor. 